This invention relates to improvements in foaming devices and more particularly, it concerns a low-cost foam generating and dispensing apparatus by which a foamable liquid having a relatively high solids content may be mixed with gas, such as air, and simultaneously dispensed as foam.
Since the introduction and popularization of aerosol dispensers, a wide variety of foam products have been available to the consuming public including, for example, cosmetics such as shaving creams, facial cleansing soaps and lotions, hair setting lotions and hair color foams; cleaning products such as upholstery cleaners, carpet shampoos, floor waxes and cleaners, furniture polishes and cleaners, and oven cleaners; medical products such as pain killers, burn treatments, antibiotic lotions and the like; and food products such as cake toppings, whipped desserts, salad dressings and various sauces. Because of the desirable characteristics of using these and many other products as a foam, in contrast to a liquid spray, and because of the ease with which aerosol dispensers may be handled, a substantial market has been generated for foamed or foamable products. Shortcomings of aerosol dispensers have been receiving considerable attention of late, however, such as the collective discharge of sufficient quantities of freon and other gases used in aerosol dispensers to have an adverse effect on the environmental quality of the atmosphere, increasing costs of materials required for aerosol containers and increasing manufacturing costs required for the fabrication, assembly and filling of aerosol dispensing units. As a result, manually operated dispensers are being looked to as a potential substitute for foamable products heretofore supplied only in pre-pressurized aerosol dispensers.
As compared with pressurized aerosol dispensers, manually operated foaming devices must be operated with limited and thus relatively low dispensing pressures. Provision must be made, therefore, for mixing air and foamable liquid under conditions which will produce foam of predictably uniform consistency such as by the forced collapse of a bottle containing air and the foamable liquid while maintaining resistance to dispensing flow at a minimum. Such conditions have been met in the past by discharging the air and foamable liquid through a porous element of material providing minute tortuous passages in which a highly turbulent flow of the liquid and air results in the appropriate mixing and homogenization of the discharged foam. See, for example, U.S. Pat. Nos. 2,680,010 issued June 1, 1954 to F. X. Dubay; 3,422,993 issued Jan. 21, 1969 to G. E. Boehm et al; and 3,709,437 issued Jan. 9, 1973 to H. E. Wright.
In a copending application of Jack C. Gardner, Ser. No. 584,610 filed June 6, 1975, now U.S. Pat. No. 3,985,271, and assigned to the assignee of the present invention, there is disclosed a manually actuated foaming device capable of generating and dispensing a highly consistent foam under pressures developed manually to displace foamable liquid and air directly through a porous member preferably formed of a sintered agglomerate of thermo-plastic particles. Because of its effectiveness in operation and also in light of its potential for low-cost manufacture, the foam generating and dispensing device disclosed in this copending application is believed to represent a viable substitute for pressurized aerosol dispensers particularly in connection with foamable liquid products having little or no solids content which would interfere with the passage of the liquid through the porous member.
Many of the foamable liquid products heretofore available in pressurized aerosol containers are known to contain a relatively high percentage of crystalline, fibrous or particulate solids. Floor and furniture waxers and polishers, for example, contain a substantial proportion of crystalline solids whereas food products are likely to contain a high fibrous solid content. Also, many cosmetic products contain a high percentage of particulate solids for fillers or for color pigments. The relatively sophisticated structure of pressurized aerosol containers as well as the relatively high gas pressures available in such dispensers have contributed to the avoidance of problems associated with a high solids content of the product to be foamed. The problem, however, is acute in connection with manually actuated foaming devices.